The present invention concerns a method and a device for recording and reading audio and/or video information broadcast as individual programs on one or more channels by air broadcasting, satellite or cabled network.
Recent developments of the audiovisual techniques have led, in a number of countries, to a choice of TV programs exceeding the viewers"" capacity to view all the programs of interest. This is particularly noticeable in countries having satellite TV, notably providing digital transmissions, and cable networks. In practice a TV viewer watches only one channel at a time, possibly recording another program on his video cassette recorder (VCR) at the same time.
A problem arises when the viewer is interested in several programs broadcast at the same time or when several members of his family with different tastes share the same TV set. To resolve this problem, one solution would be simply to acquire more TVs and VCRs, but this solution is costly and the correction and use of several recorders in parallel can be problematic.
A viewer may also wish to record a number of TV programs when he is not watching the television (during the day when he is at work, or during the night). The present solution is to program the video recorder to record sequentially in time a number of programs selected in advance. However, a problem arises if the programs are not broadcast at the time announced; there is also the problem of the limited recording capacity (a few hours at most) of present video cassettes. These constraints seriously limit the freedom of the user to record programs of interest.
In parallel with a rapid increase in the number of TV channels broadcast live, a number of supplementary services are now offered. For example, xe2x80x9con-demand videoxe2x80x9d services enables the consumer to select a movie in a server system that then starts sending the program to the user in exchange for a payment. Such a system requires a server of large-capacity and a wide band network in order to be able to respond to simultaneous requests for different movies from a large number of consumers. The consumer is totally dependent on the state of operation of the network and the catalogue of the movies offered by the server.
The present invention proposes a technique that enables a consumer to have a large-capacity recording device at home to in order to be able to build a personal video and/or audio library.
Another object of the invention is to offer the consumer a genuine on-demand video service in which he totally controls the selection and display of the programs from his own video reservoir.
Another object of the invention is to enable the program supplier to assure the revenues generated by his programs by controlling the access to video and/or audio programs recorded consumer""s recording device, and/or by encrypting the broadcast programs.
Another object of the invention is to enable the consumer to control access to his video and/or audio reservoir by means of a personal access code, and/or limit his expenditure on decoding of certain of the recorded programs by choosing only to display or listen to program of interest.
Another object of the invention is to enable the consumer to constitute a video or audio library in his recording device whose content is controlled by the consumer.
Another object of the invention is to offer a video and/or audio reservoir whose content is regularly updated by the broadcasters, the consumer being able to watch recorded programs during the update of the content of his video and/or audio reservoir.
The invention is therefore a method of recording and reading audio and/or video information broadcast as individual programs via one or several channels by air broadcasting, satellite or cable network. The method comprises the following steps:
select at least one channel to receive;
digitally encode the received signals;
record the encoded digital signals on a large-capacity recording medium;
create an index on the recording medium for each individual program recorded;
create at least one menu of recorded programs;
select one or several programs from a menu of recorded programs displayed on a screen;
read said selected program(s);
decoding the signals read;
reproduce the corresponding audio and/or video information.
The received signals may be either analog or digital. In case of analog signals received, an analog to digital conversion is done.
The method can include an access control stage to enable reading of at least one of the recorded programs. The use of one or more access codes enables access to the recorded programs to be modulated by applying criteria defined by broadcasters and by the consumer. In this way the broadcasters can control the access to certain types of programs, and modulate the amount of the subscription that the consumer must pay to obtain access to these programs. The same applies when several broadcasters offer programs with different subscriptions from one broadcaster to another. On the user side, the access code enables him to totally prevent other persons from accessing the service, or prevent children accessing programs intended only for adults.
The method of the invention also provides the possibility of recording encoded programs and decoding them during the reading by means of a specific code, in order to reproduce the sound or images. Such as service enables the consumer to control his expenditure on decoding of certain of the recorded programs. The specific code could be the number of his bank card or credit card, so that he pays each time he wishes to decode a program.
The recording and reading functions are advantageously independent of each other, in order to allow reading of one or more recorded programs while recording other programs. The consumer is then able to update the content of his video and/or audio reservoir at any time.
The method preferably enables programs designated by the user to be locked, so that they can not be erased. In this way the user can build up a personal collection of protected recordings. To delete one of the recordings, the user must first unlock it, then erase it from the recording medium.
Advantageously, the method enables simultaneous recording and/or reading of several programs in order to enable the user more rapid updating of his video and/or audio reservoir, and greater flexibility in the restitution of recorded programs, for example by using several televisions sets in parallel to display several recorded programs at the same time. The same applies for audio programs. Several members of the family can then view or listen to the recorded programs independently in different rooms.
The invention also includes a recording and reading device, referred to as a xe2x80x9cvideo and/or audio reservoirxe2x80x9d, implementing the method according to the invention, this device including:
means of reception frequency selection enabling reception of one or more broadcasting channels simultaneously;
means of digital encoding of the received signals;
means of recording and reading said encoded digital signals;
means of control enabling the recording and reading of programs to be controlled independently;
means of processing the signals read in order to reproduce the sound and/or image (possibly with the ability to read and reproduce in parallel several recorded programs, simultaneously and independently from one another).
Said means of recording and reading must include a large-capacity recording medium in order to enable a xe2x80x9creservoirxe2x80x9d to be constituted. The reservoir must be capable of storing a large number of video and/or audio programs (music, news, conferences, etc.).
The French patents Nxc2x02 630 853, Nxc2x02 656 723 and Nxc2x02 699 724 describe a technique of recording and reading on a magnetic tape that enables the storage of a large amount of information. Schematically, the technique uses a magnetic tape that moves over a static magnetic recording head composed of a matrix of Nxc3x97M individual recording elements (Nxe2x89xa72 and Mxe2x89xa71). By using protocols of excitation of the individual recording elements it is possible to record up to N parallel tracks of information. For the reading of the magnetic tape, a static magneto-optical head enables polarized light to be projected on the magnetic tape which, by the Kerr effect changes the optical polarization when it is reflected from the magnetic tape as a function of the magnetic polarization of the illuminated tracks. A sensor converts the reflected polarized light into a stream of binary numbers representing the data recorded on the N parallel tracks. The patents mentioned above contain more detail of the technique concerned which, by use of the matrix head, enables recording and reading on N parallel tracks on the magnetic tape, simultaneous, independent recording and reading of several programs, and increase of the storage capacity of a 8 mm magnetic tape cassette up to about a hundred hours of video programs.
It is also possible to use the technique of the digital video cassette to build the video and/or audio reservoir. The technique consists in recording and reading information on a magnetic tape by means of a rotating head. Using digital compression, the cassette is capable of storing up to several tens of hours of video programs. Given that the recording and reading data rate on the cassette is several times greater than the broadcasting rate of video programs on a channel (1 to 8 Mbits/s), it is possible to envisage the recording in parallel of several programs by means of a special multiplexing protocol, and the reading of these programs in parallel by means of a demultiplexing protocol. The user can then view one or more programs that are read in parallel.